Method of producing building board



Patented May 19, 1931 UNITED STATES PATENT OFFICE CARL-JOHAN H. N ORDENSWAN, OF WILMINGTON, DELAWARE, ASSIGNOR TO HERCULES POWDER COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE METHOD or PRODUCING BU'ILDING BOARD No Drawing.

My invention relates to a method of producing building board and more particularly to the production of building board from resinous wood.

Heretofore building board has been produced principally from pulp screenings, waste paper, bagasse, straw and the like, it having been found essential from the practical standpoint to avoid the use of highly resinous woods, since the resins exude in the defibering process and stick to the mill, interfering with its operation, and in the defibering process preventing hydration, so that the fibres do not interlockl Attempts have been made to enable the use of highly resinous woods by treatment for the elimination of the resins, but such attempts involving digesting of the 'WOOCl with an alkali, sulphate or sulphite, or by a semi-chemical process using sodium bicarbonate have proved impractical due to high consumption of chemicals and substantial plant investment required. Such processes are further disadvantageous as they do not leave the treated wood in a condieffect the removal of relatively volatile resinous constituents, as turpentine and pine oil when pine wood is used. The chipped wood is then extracted with a solvent for the less volatile resinous constituent-s, as rosin in the case of pine wood. The steamed wood may be extracted, for example, with gasoline, naptha, or other light hy rocarbon distillate or mixtures thereof solvent of the resin content of the wood.

After the extraction of the wood with a solvent and drawing oif of the solvent, the wood is desirably heated for the removal Application filed February 24, 1928. Serial No. 256,819.

and then in admixture with water formedinto sheets, subjected to pressure and dried.

In the treatment of the resinous wood according to the method embodying my invention where pine wood is treated, the turpentine and pine oil may be recovered and separated. The rosin may also .be recovered from the solvent by which it is extracted, by evaporation off of the solvent, whichmay be reused for further extraction.

The method in accordance .with my in-. vention enables the production of building board from highly resinous woods, as )ine wood, and enables the production trom down wood, stumps and the like. At the same time valuable by-products, as turpentine, pine oil and rosin, are obtained. The wood treated in accordance with my invention' is substantially un hanged physically and lends itself desirably to the production of building board, while at the same time affording a minimum cost raw material for the purpose.

Havingnow fully described. my invention, what I claim and desire to protect by Letters Patent is The method of producing building board which includes heating pine wood to effect the removal of turpentine and pine oil therefrom, treating the wood with gasoline for the extraction of rosin therefrom, mechanically defibering the wood, forming the wood in admixture with water into a sheet and eliminating the water from the sheet.

In testimony of which invention, I have hereunto set my hand, at WVilmington, Del., on this 18th day of February, 1928.

CARL-JOPIAN H. NORDEN SWAN. 

